/*      driver for lmstr example. */

#include <stdio.h>
#include <math.h>
#include <assert.h>
#include <minpack.h>
#define real __minpack_real__

void fcn(const int *m, const int *n, const real *x, real *fvec, real *fjrow, int *iflag);

int main()
{
  int i, j, m, n, ldfjac, maxfev, mode, nprint, info, nfev, njev;
  int ipvt[3];
  real ftol, xtol, gtol, factor, fnorm;
  real x[3], fvec[15], fjac[3*3], diag[3], qtf[3], 
      wa1[3], wa2[3], wa3[3], wa4[15];
  int one=1;

  m = 15;
  n = 3;

  /*      the following starting values provide a rough fit. */

  x[1-1] = 1.;
  x[2-1] = 1.;
  x[3-1] = 1.;

  ldfjac = 3;

  /*      set ftol and xtol to the square root of the machine */
  /*      and gtol to zero. unless high solutions are */
  /*      required, these are the recommended settings. */

  ftol = sqrt(__minpack_func__(dpmpar)(&one));
  xtol = sqrt(__minpack_func__(dpmpar)(&one));
  gtol = 0.;

  maxfev = 400;
  mode = 1;
  factor = 1.e2;
  nprint = 0;

  __minpack_func__(lmstr)(&fcn, &m, &n, x, fvec, fjac, &ldfjac, &ftol, &xtol, &gtol, 
                          &maxfev, diag, &mode, &factor, &nprint, &info, &nfev, &njev, 
                          ipvt, qtf, wa1, wa2, wa3, wa4);
  fnorm = __minpack_func__(enorm)(&m, fvec);

  printf("      final l2 norm of the residuals%15.7g\n\n", (double)fnorm);
  printf("      number of function evaluations%10i\n\n", nfev);
  printf("      number of Jacobian evaluations%10i\n\n", njev);
  printf("      exit parameter                %10i\n\n", info);
  printf("      final approximate solution\n");
  for (j=1; j<=n; j++) {
    printf("%s%15.7g", j%3==1?"\n     ":"", (double)x[j-1]);
  }
  printf("\n");
  ftol = __minpack_func__(dpmpar)(&one);
  {
    /* test the original covar from MINPACK */
    real covfac = fnorm*fnorm/(m-n);
    __minpack_func__(covar)(&n, fjac, &ldfjac, ipvt, &ftol, wa1);
    printf("      covariance\n");
    for (i=0; i<n; ++i) {
      for (j=0; j<n; ++j) {
        printf("%s%15.7g", j%3==0?"\n     ":"", (double)(fjac[i*ldfjac+j]*covfac));
      }
    }
    printf("\n");
  }

  return 0;
}

void fcn(const int *m, const int *n, const real *x, real *fvec, real *fjrow, int *iflag)
{

  /*      subroutine fcn for lmstr example. */

  int i;
  real tmp1, tmp2, tmp3, tmp4;
  real y[15]={1.4e-1, 1.8e-1, 2.2e-1, 2.5e-1, 2.9e-1, 3.2e-1, 3.5e-1,
              3.9e-1, 3.7e-1, 5.8e-1, 7.3e-1, 9.6e-1, 1.34, 2.1, 4.39};
  assert(*m == 15 && *n == 3);

  if (*iflag == 0) {
    /*      insert print statements here when nprint is positive. */
    /* if the nprint parameter to lmder is positive, the function is
       called every nprint iterations with iflag=0, so that the
       function may perform special operations, such as printing
       residuals. */
    return;
  }
  
  if (*iflag < 2) {
    /* compute residuals */
    for (i = 1; i <= 15; i++) {
      tmp1 = i;
      tmp2 = 16 - i;
      tmp3 = tmp1;
      if (i > 8) {
        tmp3 = tmp2;
      }
      fvec[i-1] = y[i-1] - (x[1-1] + tmp1/(x[2-1]*tmp2 + x[3-1]*tmp3));
    }
  } else {
    /* compute Jacobian row */
    i = *iflag - 1;
    tmp1 = i;
    tmp2 = 16 - i;
    tmp3 = tmp1;
    if (i > 8) {
      tmp3 = tmp2;
    }
    tmp4 = (x[2-1]*tmp2 + x[3-1]*tmp3); tmp4 = tmp4*tmp4;
    fjrow[1-1] = -1.;
    fjrow[2-1] = tmp1*tmp2/tmp4;
    fjrow[3-1] = tmp1*tmp3/tmp4;
  }
  return;
}
